Is it possible to transmit any audio file in a frequency of choice and have signal capable of being received by ordinary radio devices? Also I would like to have this application controlled by an android application which would output the audio file and the desired frequency and then launch the arduino application to complete the task with these attributes. Is this possible? If any declarations are needed please ask. Thanks in advance.
Can you afford the fine for transmitting without a license?
Weedpharma
It is for a project I am working on. It is not going to be used very much, I am currently concerned with the technical aspects of it.
I'm sure the general answer to your question is YES.
If you mean can it be done with an Arduino the probable answer is NO.
As you have provided no technical details how can you expect a more useful answer.
2.4GHz and 433MHz frequencies are unregulated in many jurisdictions. The frequencies used for regular broadcast radio are not and people will not thank you for interfering with their favourite programs. Finding an illegal transmitter is not difficult.
...R
I was thinking of a short range transmitter which would be used to showcase its capabilities, I am not planning on interfering with other broadcasts, I have no reason to do so. So the idea is that somehow I connect my cell phone with the arduino (wired/wireless connection). Then I output the audio file I wish to transmit as well as the desired frequency. It would also be very useful if I could control the playback using the phone. This is the idea behind the project.
It used to be possible to buy gadgets that would take an audio input and output an FM radio signal so you could listen the the audio on your car radio (before Bluetooth and IPod connections).
...R
Can you please link me something that could possibly prove useful to this project?
Joseph_Arvanitis:
Can you please link me something that could possibly prove useful to this project?
I don't have any links and you can use Google as well as I can.
...R
Robin2:
I don't have any links and you can use Google as well as I can....R
This is an assumption as we do not know how well you can use google. 
Weedpharma
weedpharma:
This is an assumption as we do not know how well you can use google.
Pedant!
I guess I should have said "as easily"
...R
Robin2:
Pedant!...R
A badge I wear with honour!
I am not planning on interfering with other broadcasts, I have no reason to do so.
No you might not plan to but you might inadvertently do so. That is why if you get caught they confiscate all your equipment and you get a fine and possible a jail sentence.
You are only permitted to operate "type approved" transmitters in the non licensed band and an Arduino is not a type approved transmitter.